Compounds and systems for the controlled release of a specific ligand have been the subject of considerable research and product development for a variety of different applications For example, enzymes and enzyme-conjugates are well recognized reactants in immunoassays for reaction with specific substrates by which a variety of different chromophoric and fluorescent dyes are released. These enzymes and enzyme-conjugates are utilized in mobile and immobilized formats in which the rate of enzymatic reaction and/or the concentration of enzyme reaction product provides qualitative and quantitative data. Illustrative of such enzyme release systems are U.S. Pat. Nos. 4,423,143; 4,501,692; 4,318,846; 4,351,760; 4,439,356; 4,447,527; and 4,481,136.
Alternatively, non-enzymatic release systems are also conventionally known, a representative example being displacement reaction mechanisms and release systems used in photographic processes for the release of color-imaging compounds. Such compounds, in the presence of oxidized color developing agents, typically undergo an intramolecular displacement reaction to form a new heterocyclic ring; and as a function of such displacement reaction mechanism and ring formation, split off mobile and diffusible color-imaging material. Such non-enzyme release systems and compositions reflect the pioneer work of Messrs. Raiford and Inman [J. Amer. Chem. Soc. 56:1586 (1934)]and Messrs. Hutchins and Fife [J. Amer. Chem. Soc. 95:7 (1973)]; illustrative examples of the displacement reaction release mechanism as it relates to photographic processes and compositions are described in U.S. Pat. Nos. 3,443,939; 3,443,940; 3,751,406; 3,980,479; and 4,139,379.
Despite the ongoing innovations and developments in each of these respective technical areas, there has been no overlap or merger of these individual controlled release techniques. Although the benefits and advantages of such a potential merger between enzymes and compositions able to undergo an intramolecular displacement reaction are substantial, there has not been any innovative development bridging the gap between these technical areas insofar as is presently known.